Heat dissipating fan

ABSTRACT

A heat dissipating fan includes a stator and a rotor. The stator includes a bearing and a winding structure, wherein the bearing is disposed in the winding structure. The rotor includes a fan wheel, a ring-shaped casing and a magnetic member, wherein the ring-shaped casing is disposed in the fan wheel and the magnetic member is disposed in the ring-shaped casing. The fan wheel has an axle inserted into the bearing such that the winding structure is located within the magnetic member. At least one protruding portion protrudes from one side of the ring-shaped casing inwardly and is extended below the winding structure so as to hold the magnetic member and interfere with the winding structure.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a heat dissipating fan and, more particularly, to a heat dissipating fan capable of holding a magnetic member stably and preventing a rotor from coming off a stator effectively.

2. Description of the Prior Art

Referring to FIG. 1, FIG. 1 is a cross-sectional view illustrating a heat dissipating fan 1 of the prior art. As show in FIG. 1, the heat dissipating fan 1 comprises a fan frame 10, a stator 12 and a rotor 14, wherein the stator 12 and the rotor 14 are disposed in the fan frame 10. The stator 12 comprises a bearing 120, a plurality of teeth 122 and a plurality of coils 124, wherein the teeth 122 are disposed around the bearing 120 and the coils 124 are wound around the teeth 122. The rotor 14 comprises a fan wheel 140 and a magnetic member 142, wherein the magnetic member 142 is attached on an inner wall of the fan wheel 140 and the fan wheel 140 has an axle 144 inserted into the bearing 120. When the heat dissipating fan 1 is powered on, the coils 124 switch magnetic pole alternately such that a magnetic force is induced between the coils 124 and the magnetic member 142, so as to drive the fan wheel 140 to rotate. Consequently, air can be guided by the fan wheel 140 to flow.

In general, the magnetic member 142 is attached on the inner wall of the fan wheel 140 by an adhesive (e.g. anaerobic adhesive) . However, the quality of the anaerobic adhesive may degrade easily after being used for a long time or under high temperature such that the magnetic member 142 may come off the fan wheel 140. Furthermore, when the rotor 14 is rotating, the rotor 14 may come off the stator 12 due to vibration induced by high speed rotation. Accordingly, the heat dissipating fan may have a breakdown or other components within an electronic device maybe damaged. Moreover, referring to FIG. 2, FIG. 2 is a cross-sectional view illustrating another heat dissipating fan 1′ of the prior art. As shown in FIG. 2, the heat dissipating fan 1′ utilizes a mylar film 16 to be a fastener for fastening the axle 144. However, the mylar film 16 may fall off easily after being used for a long time such that the rotor 14 may come off the stator 12 due to vibration induced by high speed rotation.

SUMMARY OF THE INVENTION

The invention provides a heat dissipating fan capable of holding a magnetic member stably and preventing a rotor from coming off a stator effectively, so as to solve the aforesaid problems.

According to an embodiment of the invention, a heat dissipating fan comprises a stator and a rotor. The stator comprises a bearing and a winding structure, wherein the bearing is disposed in the winding structure. The rotor comprises a fan wheel, a ring-shaped casing and a magnetic member, wherein the ring-shaped casing is disposed in the fan wheel and the magnetic member is disposed in the ring-shaped casing. The fan wheel has an axle inserted into the bearing such that the winding structure is located within the magnetic member. At least one protruding portion protrudes from one side of the ring-shaped casing inwardly and is extended below the winding structure so as to hold the magnetic member and interfere with the winding structure.

As mentioned in the above, the invention disposes the magnetic member in the ring-shaped casing and utilizes the at least one protruding portion, which protrudes from one side of the ring-shaped casing inwardly, to hold the magnetic member. Furthermore, when the axle of the rotor is inserted into the bearing of the stator, the protruding portion, which protrudes from one side of the ring-shaped casing inwardly, is extended below the winding structure so as to interfere with the winding structure. Accordingly, the protruding portion can prevent the rotor from coming off the stator when the rotor is at rest or rotating.

These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view illustrating a heat dissipating fan of the prior art.

FIG. 2 is a cross-sectional view illustrating another heat dissipating fan of the prior art.

FIG. 3 is a perspective view illustrating a heat dissipating fan according to an embodiment of the invention.

FIG. 4 is an exploded view illustrating the heat dissipating fan shown in FIG. 3.

FIG. 5 is an exploded view illustrating the heat dissipating fan shown in FIG. 3 from another viewing angle.

FIG. 6 is a cross-sectional view illustrating the heat dissipating fan shown in FIG. 3 along line X-X.

FIG. 7 is a bottom view illustrating the winding structure, the ring-shaped casing and the magnetic member shown in FIG. 6.

DETAILED DESCRIPTION

Referring to FIGS. 3 to 7, FIG. 3 is a perspective view illustrating a heat dissipating fan 3 according to an embodiment of the invention, FIG. 4 is an exploded view illustrating the heat dissipating fan 3 shown in FIG. 3, FIG. 5 is an exploded view illustrating the heat dissipating fan 3 shown in FIG. 3 from another viewing angle, FIG. 6 is a cross-sectional view illustrating the heat dissipating fan 3 shown in FIG. 3 along line X-X, and FIG. 7 is a bottom view illustrating the winding structure 322, the ring-shaped casing 342 and the magnetic member 344 shown in FIG. 6.

As shown in FIGS. 3 to 6, the heat dissipating fan 3 comprises a fan frame 30, a stator 32 and a rotor 34, wherein the stator 32 and the rotor 34 are disposed in the fan frame 30. The stator 32 comprises a bearing 320 and a winding structure 322, wherein the bearing 320 is disposed in the winding structure 322. In this embodiment, the winding structure 322 has a plurality of teeth 324 and there is a gap 326 between two adjacent teeth 324. It should be noted that the number of the teeth 324 can be determined according to practical applications and is not limited to the embodiment shown in the figures. In practical applications, a plurality of coils (not shown) is wound around the teeth 324. Furthermore, the heat dissipating fan 3 further comprises a circuit board 36 and a Hall sensor 38, wherein the Hall sensor 38 is disposed on the circuit board 36. The principle of the Hall sensor 38 is well known by one skilled in the art and will not be depicted herein.

The rotor 34 comprises a fan wheel 340, a ring-shaped casing 342 and a magnetic member 344, wherein the ring-shaped casing 342 is disposed in the fan wheel 340 and the magnetic member 344 is disposed in the ring-shaped casing 342. As shown in FIGS. 5 and 6, at least one protruding portion 346 protrudes from one side of the ring-shaped casing 342 inwardly. In this embodiment, four protruding portions 346 protrude from one side of the ring-shaped casing 342 inwardly and are corresponding to four gaps 326 between four teeth 324. It should be noted that the number of the protruding portions 346 can be determined according to practical applications and is not limited to the embodiment shown in the figures. To assemble the rotor 34, an operator has to attach the magnetic member 344 on an inner wall of the ring-shaped casing 342. At this time, the protruding portions 346 can hold the magnetic member 344. Afterward, the operator disposes the ring-shaped casing 342 with the magnetic member 344 into the fan wheel 340. Accordingly, when the rotor is rotating, the protruding portions 346 of the ring-shaped casing 342 can hold the magnetic member 344 stably even without any adhesive (e.g. anaerobic adhesive) or under high temperature so as to prevent the magnetic member 344 from coming off the ring-shaped casing 342.

Furthermore, the fan wheel 340 has an axle 348. In this embodiment, a width W of the protruding portion 346 is smaller than the gap 326 between two adjacent teeth 324. Accordingly, the operator can align the protruding portions 346 of the rotor 34 with the gaps 326 between the teeth 324 correspondingly, make the protruding portions pass through the gaps 326, and insert the axle 348 into the bearing 320 of the stator 32 such that the winding structure 322 is located within the magnetic member 344, as shown in FIG. 5. In this embodiment, a length L of the protruding portion 346 covers a gap 328 between the magnetic member 344 and the teeth 324 such that the protruding portions are extended below the teeth 324 of the winding structure 322 after the rotor 34 and the stator 32 are assembled.

When the heat dissipating fan 3 is powered on, the coils (not shown), which are wound around the teeth 324, switch magnetic pole alternately such that a magnetic force is induced between the coils and the magnetic member 344, so as to drive the fan wheel 340 to rotate. Consequently, air can be guided by the fan wheel 340 to flow. The protruding portions 346 interfere with the teeth 324 of the winding structure 322 in an axial direction of the axle 348, so as to prevent the rotor 34 from coming off the stator 32 when the rotor 34 is at rest or rotating. It should be noted that the protruding portions 346 may be extended below other portions of the winding structure 322 except the teeth 324, so as to interfere with other portions of the winding structure 322 when the rotor 34 is at rest or rotating.

In this embodiment, the ring-shaped casing 342 may be made of, but not limited to, a magnetic induction material, wherein the magnetic induction material may be, but not limited to, electro-galvanized steel (SECC). Accordingly, a magnetic attraction force can be induced between the magnetic member 344 and the ring-shaped casing 342 such that the magnetic member 344 can be attached on the inner wall of the ring-shaped casing 342 by the magnetic attraction force without the aforesaid adhesive.

As mentioned in the above, the invention disposes the magnetic member in the ring-shaped casing and utilizes the at least one protruding portion, which protrudes from one side of the ring-shaped casing inwardly, to hold the magnetic member. Furthermore, when the axle of the rotor is inserted into the bearing of the stator, the protruding portion, which protrudes from one side of the ring-shaped casing inwardly, is extended below the winding structure so as to interfere with the winding structure. Accordingly, the protruding portion can prevent the rotor from coming off the stator when the rotor is at rest or rotating.

Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims. 

What is claimed is:
 1. A heat dissipating fan comprising: a stator comprising a bearing and a winding structure, the bearing being disposed in the winding structure; and a rotor comprising a fan wheel, a ring-shaped casing and a magnetic member, the ring-shaped casing being disposed in the fan wheel, the magnetic member being disposed in the ring-shaped casing, the fan wheel having an axle inserted into the bearing such that the winding structure is located within the magnetic member, at least one protruding portion protruding from one side of the ring-shaped casing inwardly and being extended below the winding structure so as to hold the magnetic member and interfere with the winding structure.
 2. The heat dissipating fan of claim 1, wherein the winding structure has a plurality of teeth and a width of the at least one protruding portion is smaller than a gap between two adjacent teeth.
 3. The heat dissipating fan of claim 1, wherein the winding structure has a plurality of teeth and a length of the at least one protruding portion covers a gap between the magnetic member and the teeth.
 4. The heat dissipating fan of claim 1, wherein the ring-shaped casing is made of a magnetic induction material.
 5. The heat dissipating fan of claim 4, wherein the magnetic induction material is electro-galvanized steel (SECC). 